This specification relates to clustering digital images.
Search engines process queries and return search results in response to the queries. The search results are drawn from a collection of resources that can be limited to a single type of media. For example, some search engine systems access information on thousands of image resources and provide, in response to a query, a set of image search results that identify a subset of the image resources. The search results can include a thumbnail image of an image resource. Returned image search results can be responsive to a single query but can be associated with image resources depicting numerous subject matters. For example, a search for “Paris” can return search results with thumbnails depicting Paris Hilton, the Eiffel Tower, and maps of the city Paris. A user of an image search engine may be particularly interested in image resources relating to one of these subject matters.